
function getXMLHttpRequest() {
    var xhr = null;
     
    if (window.XMLHttpRequest || window.ActiveXObject) 
    {
        if (window.ActiveXObject) 
        {
            try 
            {
                xhr = new ActiveXObject("Msxml2.XMLHTTP");
            } 
            catch(e) 
            {
                xhr = new ActiveXObject("Microsoft.XMLHTTP");
            }
        }
        else 
            xhr = new XMLHttpRequest(); 
    }
    else 
    {
        alert("Votre navigateur ne supporte pas l'objet XMLHTTPRequest.");
        return null;
    }
     
    return xhr;
}

function getADCDate(date) {
	xhr = getXMLHttpRequest();
	xhr.open("GET","index.php?module=administration&action=tableauDeBord&dateButoirADC="+date.value(), true);
	xhr.send(null);
}

<bouton type="date" name="dateA" value="<?php echo date_format($dateA, 'Y-m-d')?>" min="<?php echo $dateJour?>" onBlur="getADCdate(this)"/>